In a Gustave Caillebotte 
In a Gustave Caillebotte painting named for one of these objects, a dog walks by a man who holds his
 head in his hands. Silvano Vinceti claimed that the numbers two and seven were hidden in one of these
 objects in the background of the Mona Lisa. The title fireworks show of James Whistler's Nocturne in
 Black and Gold takes place over one of these objects. One of these objects named "Maidenhead" is thought
 to have inspired the one J.M.W. Turner painted in Rain, Steam and Speed. A Japanese inspired structure of
 this type at Giverny was often painted alongside water lilies by Claude Monet. For 10 points, name these
 structures which Canaletto often painted crossing the canals of Venice.
In a Gustave Caillebotte painting named for one of these objects, a dog walks by a man who holds his
 head in his hands.
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